The subject matter disclosed herein relates generally to ultrasound systems, and more particularly, to methods and systems for performing spatial and elevation compounding using an ultrasound system.
Ultrasound imaging is a medical imaging technique for imaging organs and soft tissues in a human body. Ultrasound imaging uses real time, non-invasive high frequency sound waves to produce a two-dimensional (2D) image and/or a three-dimensional (3D) image. In conventional ultrasound imaging, the image is acquired by a series of scan lines. This results in an image in which some anatomical structures may be “shadowed” by objects closer to the transducer and diagonal structures may not be optimally imaged. Typically, when the boundaries of anatomical structures are parallel to the transducer, the acoustic waves reflect directly back to the transducer with less dispersion and a clear image is obtained. However, diagonal or vertical structures are sub-optimally imaged using conventional ultrasound because of the lower percentage of acoustic energy that reflects back to the transducer. Furthermore, structures that are hidden beneath strong reflectors are also sub-optimally imaged. For example, a small breast cyst may be hidden behind muscular tissue (e.g., tendons), which is a strong superficial reflector.
In addition, another disadvantage of conventional ultrasound imaging is speckle noise. Speckle noise is a result of interference of scattered echo signals reflected from an object, such as an organ. The speckle appears as a granular grayscale pattern on an image. The speckle noise degrades image quality (e.g., speckles obtained from different angles are incoherent) and increases the difficulty of discriminating fine details in images during diagnostic examinations.
At least some known ultrasound systems are capable of spatially compounding a plurality of ultrasound images of a given target into a compound image. The term “compounding” generally refers to non-coherently combining multiple data sets to create a new single data set. The plurality of data sets may each be obtained from imaging the object from different angles, using different imaging properties (such as e.g. aperture, frequency) and/or imaging nearby objects (such as slightly out of the plane steering). These compounding techniques can be used independently or in combination to reduce speckle and improve image quality.
The plurality of data sets or steering frames are combined to generate a single view or compound image by combining the data received from each point in the compound image target that has been received from each compound frame. A transducer array may be utilized to implement electronic beam steering and/or electronic translation of the component frames. The component frames are combined into a compound image by summation, averaging, peak detection, or other combinational means. The compounded image may display relatively lower speckle and better specular reflector delineation than a non-spatially compounded ultrasound image.